1. Field of the Invention
This invention relates to circuit arrangements for providing a store of electrical energy for actuating an electrically operable device, more especially for altering the state of a magnetic actuator in order to effect the opening or closing of an associated circuit breaker.
2. Description of Related Art
Such a circuit arrangement may, for example, incorporate a large reservoir capacitor which, when fully charged, stores sufficient energy to permit several close/open operations constituting an auto-reclose cycle of the circuit breaker, ending in the circuit breaker locked out in the open position, in the event of a fault in the line controlled by the circuit breaker to clear by the end of the cycle.
A typical auto-reclose cycle can, for example, take the form EQU o-t-co-t'-co-t"-co
or alternatively EQU co-t-co-t'-co-t"-co
where
c=closing operation
o=opening operation, and
t, t', t" are increasing time intervals in the range 0.3 to several seconds, which can be set as required. After the cycle has been completed, a relatively long time interval, of the order of minutes, would then be available for re-charging of the reservoir capacitor in readiness for further operations.
Although re-charging of the reservoir from a conventional voltage transformer and rectifier connected to the supply side of the circuit breaker is technically sound, it incurs considerable expense in order to provide the relatively low power required for this purpose.